The number of procedures performed by the operator of a Percutaneous Coronary Intervention (PCI) in the previous year has no impact on the 30-day mortality, according to a recent UK study published in the European Heart Journal.
Two previous studies have associated increased number of procedures performed by the operator with less in-hospital mortality and major adverse cardiovascular outcomes (MACE). However, authors argue that these studies were conducted before 2010. The use of transradial approach has increased from 16% to 75% between 2005 and 2014 in the UK. Transradial PCIs tend to be performed by more experienced operators and this might have had an impact on the outcome. Two other studies on the same topic were done after 2010. However, the operator volume in both of them was much lower than that of the current study. The median operator volume in the study was 178 procedure per year which is higher than the median operator volume in many other countries.
Dr. Davide Capodanno, the Associate Professor of Cardiology at the University of Catania comments in the accompanying editorial saying, “These figures should be considered when generalizing the study findings outside the boundaries of the UK, where many countries have lower operator volumes.”
[perfectpullquote align=”full” bordertop=”false” cite=”” link=”” color=”” class=”” size=””]”The most important message of this study is that mortality is a weak endpoint when looking at operators’ proficiency.” – Dr. Davide Capodanno[/perfectpullquote]
The study was conducted on 134,000 patients from the British Cardiovascular Intervention Society PCI database. Comparing high to low volume operators, there was no significant difference between the 30-day mortality among the two groups with an odds ratio of 0.99. The findings were the same when the operator volume was plotted as a continuous or dichotomous predictor.
“The authors must be congratulated for proficiently undertaking complex statistical modeling that accounts for the operator- and center-level clustering to look at the volume-outcome relationship”, says Dr. Capodanno.
The authors acknowledge the absence of randomization as the major limitation of the study. However, many confounders have been adjusted for such as the center volume and patient-related risk factors. Also, MACE and in-hospital mortality could not be validated and thus were reported as secondary outcomes. Dr. Capodanno adds, “The principal outcome measure was 30-day mortality, one of the rarest complications of PCI. Also importantly, separate analyses in high-risk clinical subsets (e.g. left main or chronic total occlusion PCI) are not available.”
Dr. Capodanno concludes, “The most important message of this study is that mortality is a weak endpoint when looking at operators’ proficiency.” He also says, “Volumes should not be surrogates for prospectively monitored and properly risk-adjusted outcomes.”